\\[-1.8ex] Soil Heterogeneity & $-$4.508$^{***}$ & $-$3.966$^{***}$ & $-$2.542$^{***}$ & $-$2.405$^{***}$ \\ 
  & (1.172) & (1.102) & (0.741) & (0.725) \\ 
\\[-1.8ex] 
Observations & 7,484 & 7,484 & 2,038 & 2,038 \\ 
R$^{2}$ & 0.644 & 0.669 & 0.594 & 0.598 \\ 
